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XOR and the Need for Representation

Boolean Input

A Boolean input is a value with two possible states, usually represented as 0 or 1.

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Boolean Input

Definition

A Boolean input is an input with two possible values.

Common values:

0
1

or:

false
true

Boolean input = input with two possible states.


Boolean Values As Symbols

Boolean values can be represented by symbols.

Example:

0 = false
1 = true

The symbols 0 and 1 are not the only possible representation.

We could also write:

F and T
No and Yes
Off and On

The important part is that the two states are distinguishable and used consistently.

Boolean values are two-state symbols.


Boolean Input As Vector Data

Two Boolean inputs can be represented as a vector.

Example:

x = [x1, x2]

where each component can be:

0 or 1

Possible inputs:

[0, 0]
[0, 1]
[1, 0]
[1, 1]

Boolean inputs can still be treated as vector data.


Discrete Input

Boolean input is discrete.

There are no values between:

0 and 1

in the Boolean setting.

The input is either one state or the other.

Boolean values are separate possibilities, not continuous measurements.


Why Boolean Inputs Matter For XOR

XOR uses two Boolean inputs.

Example:

x1 = 0
x2 = 1

The output is also Boolean:

0 or 1

This makes XOR small enough to list completely.

XOR is built from two Boolean inputs and one Boolean output.


Boolean Does Not Mean Simple For Linear Models

Boolean inputs are simple as values.

But their class pattern can still be difficult for a linear classifier.

XOR is the key example.

It has only four possible inputs, but one straight line cannot separate its classes.

Simple inputs can still create nonlinearly separable patterns.


Final Summary

  • A Boolean input has two possible values.
  • Common encodings are 0/1 or false/true.
  • Boolean values are symbols used consistently.
  • Two Boolean inputs can form a vector.
  • Boolean inputs are discrete.
  • XOR uses two Boolean inputs.
  • Simple Boolean input can still expose limits of linear classification.

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Continue the series.

XOR Definition